An air handling unit is widely used in an all-air air conditioning system. According to statistics, almost 120 thousands air handling units of each type are needed in currently market, every year. Actually, one million air handling units are almost used.
A modular air-conditioning unit is the most important device of an air handling system. The modular air-conditioning unit at least includes several functions as bellow: transport, heating, cooling, humidification, dehumidification, filtration, sound absorption, and heat recollection. According to parameters of climate and air environment, each system is defined different functions. Functions of a traditional air handling unit are in series with each other, and the traditional air handling unit manufactures productions according to the functions and operating condition. Therefore, if the air handling unit has been completely assembled, functions thereof are substantially fixed.
Our environment goes from bad to worse, so the air handling unit is required to have more and more functions. Currently, the air handling unit almost is integrated many functions together, such as primary or/and middle-effect filter, surface cooling, heating, humidification, and sterilization, which needs more energy. In the other hand, efficient air handling units become more and more popular, because energy-saving is most important. Therefore, many companies, factories and institutes devoted in energy-saving technology, and they wants to use by-pass heating-cooling coils in transition seasons to save energy. However, using the by-pass heating-cooling coil increases material and space, which is not in conformity to the concept of go green, energy-saving, environmental awareness.